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More ports ban open-loop scrubbers

29 January 2019

A number of ports have adopted a prohibition on the discharge of washwater used in ships open-loop SOx scrubbers:

These actions follow the prohibition on scrubber washwater discharge announced in November 2018 by the Port of Singapore.

IMO regulations require that ships reduce the maximum sulfur content in their fuels to below 0.5%—compared to the current 3.5%—effective January 1, 2020. In lieu of switching to low sulfur fuels, ships are allowed to install exhaust gas treatment systems (EGTS) to control SOx emissions, commonly referred to as SOx scrubbers. Most ships that already installed scrubbers opted for the least expensive open-loop systems that use seawater to absorb SOx, and then discharge it into the sea.

Under the washwater discharge prohibitions announced by ports, ship operators who installed open-loop scrubbers to avoid the use of low sulfur fuels would still need to switch to a low sulfur fuel in the affected waters.

The discharge of scrubber washwater into the sea carries a number of potential risks to the ecosystem. These include the reduction of the pH value, the increase in the chemical oxygen demand (COD) due to oxidation of sulfites carried by the effluent, temporary temperature rise, increased turbidity, and discharge of other pollutants such as heavy metals.

Source: ClassNK | World Maritime News